fix(runner): align doctor exit with readiness

[chubes4]

Summary

Fixes #11900. runner doctor previously returned exit 0 even after its completed report classified readiness as error, so the command-result envelope correctly but misleadingly reported success.

RunnerDoctorStatus is now the canonical operational verdict: ok and non-blocking warn return 0; error returns 1. The existing command-result serializer then emits success: false and status: "failed" for error reports. There is no existing report-only contract, and agent-task doctor already treats runner error as not ready, so no caller migration is required.

Verification

• cargo fmt --check
• cargo test -p homeboy-cli runner::doctor (56 passed)
• cargo test -p homeboy-cli commands::utils::response::tests::doctor_readiness_verdict_serializes_consistently_with_the_envelope (1 passed)
• cargo check -p homeboy-cli
• cargo clippy -p homeboy-cli --tests -- -D warnings remains blocked by three pre-existing homeboy-core lint failures: two needless_update diagnostics in http_api.rs and one unnecessary_sort_by diagnostic in notify_outbox.rs.

AI Assistance

OpenAI GPT-5.6 Sol via OpenCode inspected the doctor and command-result contracts, implemented the exit semantics, and added focused tests. Chris Huber remains responsible for every line.

[homeboy-ci]

Homeboy Results — homeboy

Lint

✅ review lint — passed

ℹ️ Full options: homeboy self docs commands/lint
ℹ️ Save lint baseline: homeboy review lint homeboy --baseline
Deep dive: homeboy review lint homeboy --changed-since 7d4fedd

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-lint-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-lint-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31214686051

Audit

⚠️ review audit — no measurement

Deep dive: homeboy review audit homeboy --changed-since 7d4fedd

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-audit-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-audit-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31214686051

Tooling versions

• Homeboy CLI: homeboy 0.334.0+e3d81d6c1e4f-dirty
• Extension: rust from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 14fe68af
• Action: unknown@unknown